Thermoplastic starch compositions incorporating a particulate filler component

Abstract

Thermoplastic starch compositions that include a particulate filler, e.g. an inorganic filler component, and optional fibrous component The compositions include a thermoplastic phase comprising a thermoplastic starch melt that contains, at a minimum, starch blended with an appropriate plasticizing agent under conditions in order for the starch to form a thermoplastic melt. The thermoplastic phase may also include one or more additional thermoplastic polymers and other optional reactants, liquids or cross-linking agents to improve the water-resistance, strength, and/or other mechanical properties of the thermoplastic melt, particularly upon solidification. The inorganic filler component may affect the mechanical properties but will mainly be added to reduce the cost of the thermoplastic starch compositions by displacing a significant portion of the more expensive starch or starch/polymer melt. Fibers may optionally be included in order to improve the mechanical properties of the thermoplastic starch compositions. The thermoplastic starch compositions may be shaped into a wide variety of useful articles, such as sheets, films, containers, and packaging materials. Because the thermoplastic starch compositions will typically include a thermoplastic phase that is biodegradable, and because the other components will either constitute a naturally occurring mineral and optionally a natural fiber, the overall composition will typically be more environmentally friendly compared to conventional thermoplastic materials.

Description

1. The Field of the InventionThe present invention relates to compositions and methods for manufacturing thermoplastic starch compositions and articles made therefrom. More particularly, the present invention relates to thermoplastic starch compositions that include a particulate filler component. The thermoplastic starch compositions may optionally include one or more additional thermoplastic polymers blended therewith and fibers for reinforcement.2. The Relevant TechnologyA. Sheets, Containers, and Other Articles Made From Paper, Plastic, Glass and Metal.Materials such as paper, paperboard, plastic, polystyrene, and metals are presently used in enormous quantity as printed materials, labels, mats, and in the manufacture of other articles such as containers, separators, dividers, envelopes, lids, tops, cans, and other packaging materials. Advanced processing and packaging techniques presently allow an enormous variety of liquid and solid goods to be stored, packaged, or shipped whi...

AI Technical Summary

Benefits of technology

Certain polymers may also experience degradation or partial cleavage of the polymer chain when heated in the presence of water. For example, it is known that many polyesters can experience chain degradation and reduction of molecular weight through hydrolysis reactions with water at elevated temperatures. Reducing the molecular weight of polymers tends to weaken films and other articles made therefrom. Although not known for sure, it may be possible for water to degrade or hydrolyze a significant proportion of the acetal linkages within starch molecules at elevated temperature, particularly under high shear conditions, which may reduce the molecular weight of the starch molecules to some extent. Thus, in order to prevent hydrolysis of polymer linkages within one or polymers within a thermoplastic starch melt, it may be preferable to limit t

Problems solved by technology

However, in the case where a more volatile plasticizing solvent such as water is used, and where the melting point of the starch will cause the more volatile plasticizing solvent to rapidly vaporiz